In evolving optical communication networks, the need often arises to switch an optical signal from one path to another, be it along an optical waveguide such as an optical fibre, or in free space. Optical switching arrangements may generally be classified into two categories:
(1) moving-beam switches that redirect the optical signal path between stationary waveguides or in free space, and PA0 (2) moving-fibre switches that physically change the location of optical fibres to be switched.
The switching mechanism of the present invention belongs to the former category.
An exemplary moving-beam switch that utilizes a moving mirror to perform the switching function is disclosed by Levinson in U.S. Pat. No. 4,580,873 which is incorporated herein by reference. Although Levinson's matrix switch appears to adequately perform its intended function of allowing light to be controllably transmitted to one of a plurality of destinations requires m.times.n collimating lenses coupled to input/output fibers to collimate and focus light received from input fibers and destined for output fibers respectively, it is believed too costly and somewhat complex. Aside from the cost of providing lenses, these lenses provide a collimating beam having a diameter of about 500 .mu.m. Each of the lenses occupy a space of approximately 2 mm; thus, the minimum size, for example, of a 32 channel m.times.n switch is about 6 cm or more. Fabricating a large sized monolithic device is not practicable using a single monolithic silicone substrate. Furthermore, by providing a large diameter collimated beam, the size of a movable mirror deflecting the beam is required to be at least large enough to intercept the entire beam. Such large mirrors are costly, and moving a larger mirror in and out of the path of the beam requires more energy and is more difficult. Thus, it is believed that Levinson's device is not well suited to m.times.n applications having many input and output optical fibers.
Another switch of the former category is disclosed by Benzoni in U.S. Pat. No. 5,042,889, which relates to an activation mechanism for moving a reflective element in or out of the path of a beam of light, to allow light to be either transmitted in a first position or reflected in a second position. Although Benzoni's design may provide a simpler mechanism than that of Levinson, it provides limited functionality.
There is clearly a need for an inexpensive optical switch that will allow light to be transmitted to one of a plurality of different positions.